A heating apparatus for automatically distinguishing the condition of food to be reheated

Abstract

A heating apparatus is provided with the gas sensor for detecting gas or steam generated from an object to be heated and a weight sensor for detecting the weight of the object to be heated. The signal level of the gas sensor indicates whether the change in the amount of the gas or the steam in the exhaust guide portion is a predetermined value of gas or steam generated from the object, to determine the kind and condition of the object to be heated. Also, change in the signal level of the gas sensor is compared to the predetermined value at a detection time period which is based on the weight of the food detected by the weight sensor, to decide whether to continue or stop heating.

What is claimed is: 
     
       1. An automatic heating apparatus comprising: a heating means for heating an object, said heating means operable in a plurality of different heating modes;   a first sensor means for detecting the weight of an object;   a second sensor means for detecting the amount of gas or steam generated by an object as the object is heated by said heating means;   a control means operatively connected to said heating means, said first sensor means and said second sensor means for performing a heating controlling operation during which said control means controls said heating means to operate in one of said heating modes by selecting said one of said heating modes based on the weight detected by said first sensor means and the amount of gas or steam detected by said second sensor means;   an input means operatively connected to said control means for inputting a command to said control means to initiate said heating controlling operation; and   said control means including a calculation means for calculating a detection time period based on the weight of an object detected by said first sensor means at the initiation of said heat controlling operation, a timer means for measuring the time that has lapsed from the initiation of said heating controlling operation, a comparison means for comparing the change in the amount of steam or gas detected by said second sensor means from the initiation of said heating controlling operation until said detection time period lapses with a predetermined value, identification means for categorizing the object based on the comparison made by said comparison means, and selecting means for selecting one of said heating sequences based on the categorization of the object by said identification means.   
     
     
       2. An automatic heating apparatus as claimed in claim 1, wherein said second sensor means is a humidity sensor for detecting absolute humidity.   
     
     
       3. An automatic heating apparatus as claimed in claim 1, wherein said control means performs said heating controlling operation based on the entire weight of the object disposed in the apparatus.   
     
     
       4. An automatic heating apparatus as claimed in claim 1, wherein said calculation means calculates said detection time period based on the following equation   Tw=A×W+B     wherein Tw is said detection time period, A and B are constants and W is the weight of the object detected by said first sensor means.     
     
     
       5. An automatic heating apparatus as claimed in claim 1, wherein said identification means categorizes the object on the basis of the material thereof, characteristics exhibited by the object associated with the heating thereof, and the weight of the object.   
     
     
       6. An automatic heating apparatus as claimed in claim 5, wherein said identification means categorizes the object by calculating three time periods at which a heated state of the object is evaluated, said time periods defined by the equations   TL1=A1×W+B1       TL2=A2×W+B2       TL3=A2×W+B3     wherein TL1, TL2 and TL3 are said time periods, respectively, A1, A2, A3, B1, B2 and B3 are constants and W is the weight of the object detected by said first sensor means.     
     
     
       7. An automatic heating apparatus as claimed in claim 1, wherein said identification means stores a first detecting time T1 when the object obtains a first predetermined state while being heated, stores a second detecting time T2 when the object obtains a second predetermined state while being heated, and assigns a characteristic factor to the object based on the ratio of the time lag between when the second and the first detecting times are stored to the second detecting time, and said control means causes the object to be heated an additional time equal to the product of said factor and T2.   
     
     
       8. An automatic heating apparatus as claimed in claim 1, wherein said heating modes include a heating mode in which said heating means is operated continuously, and a heating mode in which said heating means is operated intermittently.   
     
     
       9. A method of controlling the operation of a heating means of an automatic heating apparatus having a heating chamber in which an object is placeable to be heated by the heating means and a select key for initiating the operation, said method comprising the steps of: obtaining an initial weight of the object placed in the heating chamber of the automatic heating apparatus;   heating the object with said heating means;   monitoring the amount of steam or gas generated by the object as the object is heated;   calculating a detection time period based on the initial weight of the object obtained,   comparing the change in the amount of steam or gas generated by the object from the initiation of the heating of the object until the detection time period lapses with a predetermined value; and   selecting a heating mode with which to control the operation of said heating means from among a plurality of heating modes based on the comparison made with said predetermined value.